1. Field of the Invention
The present invention relates to a lens support structure for supporting lenses used in a lens optical system of a camera and the like.
2. Related Background Art
Conventionally known as a lens support structure for supporting lenses is one arranging a plurality of lenses within a lens barrel so as to secure and support them as disclosed in Japanese Patent Application Laid-Open No. HEI 7-113937. The lens support structure disclosed in the above-mentioned publication is one inserting a plurality of lenses into a lens barrel in a stacking fashion, adjusting the optical axis of each lens, injecting a filler between the peripheral face of the lenses and the inner face of the lens barrel thereafter, and curing the filler so as to secure the lenses to the lens barrel.
However, the above-mentioned lens support structure may be problematic in that the optical axis adjustment of lenses is difficult. For example, as shown in FIG. 2, when a plurality of lenses 101, 102, and 103 are inserted into a lens barrel 100 in a stacking fashion, curved surfaces of the lenses 101 to 103 come into contact with each other. When adjusting the optical axis of the lens 101 by pressing the lens 101 sideways with pins 104, the lens 101 moves along a curved lens surface, thereby not only traveling in directions orthogonal to the optical axis but also tilting as indicated by arrows in FIG. 2, whereby the optical axis O101 of the lens 101 inclines with respect to the optical axis O of the lens barrel 100. As a consequence, the optical axis adjustment of the lens 101 may not be carried out accurately.
In order to overcome such a problem, it is an object of the present invention to provide a lens support structure which can carry out appropriate axis adjustment.
For achieving such an object, the lens support structure in accordance with one aspect of the present invention is a lens support structure comprising: a first lens; a second lens; a spacer ring for separating the second lens from the first lens; and a tubular holding frame for accommodating the fist lens and the second lens, wherein the holding frame has a flat first holding surface orthogonal to a center axis thereof; wherein the first lens has an optically functioning part and is formed with a first planar part orthogonal to an optical axis of the optically functioning part, the first lens being accommodated within the holding frame with the first planar part abutting against the first holding surface; further wherein the spacer ring is formed with a flat second holding surface orthogonal to a center axis thereof, the spacer ring being attached to an outer periphery of the first lens such that the second holding surface faces the second lens; and still wherein the second lens has an optically functioning part and is formed with a second planar part orthogonal to an optical axis of the optically functioning part, the second lens being accommodated within the holding frame with the second planar part abutting against the second holding surface.
The lens support structure in accordance with another aspect of the present invention is characterized in that the holding frame is formed with a through hole penetrating through a peripheral face thereof at a position outside the spacer ring.
The lens support structure in accordance with still another aspect of the present invention comprises latching means for latching the second lens by pressing the second lens toward the spacer ring; wherein the second lens is held as being pressed against the second holding surface by the latching of the latching means; and wherein the first lens is held as being pressed against the first holding surface by the latching of the latching means by way of the second lens and spacer ring.
The lens support structure in accordance with still another aspect of the present invention is characterized in that the latching means is formed by inwardly deforming an end part of the holding frame.
According to these aspects of the present invention, the first planar part of the first lens is caused to abut against the first holding surface of the holding frame, and the second planar part of the spacer ring is caused to abut against the second planar part of the second lens, whereby the first lens can easily be moved in directions orthogonal to the optical axis together with the spacer ring along the first holding surface and second planar part. Therefore, when the outer peripheral part of the first lens is pushed with a pin and the like at the time of making, for example, the first lens can be moved in directions orthogonal to the optical axis, so as to enable appropriate optical axis adjustment without generating postural shifts in the first lens such as tilts with respect to the optical axis.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.